I seem to have a similar problem as the freeze on Linux: on Windows 10-64, version 4.1.2, I regularly get crashes when casting spells. With crash I mean the application terminating unexpectedly, without any message.
This mostly seems to happen when a (mage) spell beams (lightning bolt, sometimes magic missile). It could very well happen when it hits a(nother) monster beyond the visible map area, although I don't think it happens all the time - then the crashes would be more common I think.

Update 30/7: I've had no more crashes after reporting this - perhaps something with my graphics driver that got fixed by rebooting? Still, if a beam leaves the visible area, it takes longer than seems necessary, but that is no biggie.

Rubble tiles are improved - followed PowerWyrm's suggestions for Shockbolt tiles, and changed the Gervais tiles (a first for me!) in line with spara's requests

Thanks for fixing this. Is there some logical reason for the background of the rubble(s) always being black?

Edit: Here are my modifications to the new rubble tiles, if these are of some use or interest. First I brought the dark bits back to keep the cartoonish look instead of washed look. And then I added the standard backgrounds with three shades of gray:

@ learned the runes of RFire and RCold by wearing a wholly unIDd robe (with those runes) and eating a Mushroom of Emergency. That probably should not happen.

At present, gaining temporary resist does cause you to learn the rune if you have anything with the permanent resist equipped. I presume that this is an intended feature rather than a bug. Remember that all of the resist sources (temporary or permanent) represent magical properties that protect you from the elements. Armor of resist cold is not a down jacket, and armor of resist fire is not Nomex. Given that all the resists are magical, it sort of makes sense that when you quaff a potion of resist fire, it would cause some detectable magical resonance with your armor of resist fire.

At present, gaining temporary resist does cause you to learn the rune if you have anything with the permanent resist equipped. I presume that this is an intended feature rather than a bug. Remember that all of the resist sources (temporary or permanent) represent magical properties that protect you from the elements. Armor of resist cold is not a down jacket, and armor of resist fire is not Nomex. Given that all the resists are magical, it sort of makes sense that when you quaff a potion of resist fire, it would cause some detectable magical resonance with your armor of resist fire.

If it's a feature, no problem. However, my first impression was that it was non-intentional since I kind of assumed that runic magic is totally different from potion magic, scroll magic and book magic. Which of course might indicate that there's a non-intuitive mechanic here. Or maybe it's just me